Carbohydrate-binding antibodies are used extensively for basic research and are useful as diagnostic and therapeutic agents. They are especially useful in the field of cancer. Cancer cells undergo dramatic changes in carbohydrate expression during the onset and progression of disease. As a result, there has been considerable interest in understanding why these changes occur, how they contribute to the disease, and exploiting these changes for clinical use. For example, Unituxin (dinituximab) is an FDA approved monoclonal antibody that targets the tumor associated carbohydrate GD2 and is used to treat children with neuroblastoma. Unfortunately, there are very few good monoclonal antibodies to carbohydrates. The lack of high quality antibodies is a major barrier for the field. We are taking a multi-pronged approach to help alleviate this problem. First, we use our glycan microarray to evaluate the selectivities of existing antibodies to carbohydrates. This information is crucial for selecting the right antibody for a particular application and interpreting results. Second, we have developed a database of antibodies to carbohydrates (Database of Anti-Glycan Reagents; DAGR) that can be used to find antibodies and information about those antibodies. Third, we are studying the mechanisms by which antibodies to carbohydrates are produced in mammals. Fourth, we are using our glycan microarray to discover and engineer new antibodies to carbohydrates